Soft Solder Materials: A Guide to Features & Applications

Tin-Based Brazing Alloys

Among soft brazing materials, tin-lead brazing alloys are used the most, primarily for the soft brazing of materials such as copper, copper alloys, carbon steel, tin-plated sheets, galvanized sheets, and stainless steel. In many tin-lead brazing alloys, a small amount of Sb is added to reduce oxidation of the brazing material when in a liquid state and to improve the thermal stability of the joint.

Some tin-lead brazing alloys incorporate a small amount of Ag to reduce the erosion of the silver plating on the base material, enhance the brazing material’s creep resistance and fatigue performance, and improve the corrosion resistance of the brazed joint.

Additionally, some tin-lead brazing alloys also contain trace elements such as P and Ca, which can prevent or reduce the oxidation of the molten brazing material surface, making them particularly suitable for wave soldering and dip soldering.

Lead-Based Brazing Alloys

Lead-based brazing alloys exhibit better heat resistance compared to tin-lead brazing alloys, but they have poorer wetting properties on copper. To improve their wetting properties, a small amount of tin can be added, often supplied in a filament form.

Lead-Based Brazing Alloys

Lead-based brazing alloys exhibit better heat resistance compared to tin-lead brazing alloys, but they have poorer wetting properties on copper. To improve their wetting properties, a small amount of tin can be added, often supplied in a filament form.

Cadmium-Based Brazing Alloys

This type of brazing alloy has the best heat resistance among soft brazing materials and also possesses good corrosion resistance. Cadmium-based brazing alloys are often supplied in filament form.

Zinc-Based Brazing Alloys

Most zinc-based brazing alloys have low strength, poor ductility, and poor wetting properties on steel. Therefore, they are mainly used for brazing aluminum and aluminum alloys, and can also be used for brazing aluminum to copper and copper alloys.

Low-Melting-Point Soft Brazing Alloys

① Gallium-based brazing alloys, can be mixed with silver, copper, and nickel powders to create composite brazing materials.

During brazing, the composite brazing material is applied to the desired connection point, and then the workpiece is either pressurized or left in a free state and held at a certain temperature for 24 to 48 hours. Due to the diffusion between the liquid and solid phases, the brazed joint solidifies to form the joint.

② Bismuth-based brazing alloys, are brittle, and have poor wetting properties on copper and steel. Prior to brazing, the metal should be pre-plated with zinc, silver, or tin.

Leave a Comment

Your email address will not be published. Required fields are marked *

Scroll to Top